Boston police say they have viewed surveillance video of Tuesday’s shooting. “Clearly, it shows, our officers walking up to this individual, with no guns, and then within seconds retreating. Five policemen, backtracking, backtracking,” he said.

Rahim had originally planned to kill Pamela Geller, the organizer of the controversial "Draw Muhammad" competition, law enforcement sources told NBC News. Rahim abandoned that plan in favor of a plot to target police officers sometime this week.